I had sex for the first time, and then got my period the next day, but it was a week early. I had bleeding for 5 days which is normal for my period. Usually my cycle was every 28 days, and since I had sex, it became every 21 days for 3 months straight. However, I was supposed to get it last week and this would have been 21 days, but I didn't. I figured it was going back to normal. However, I am now 1 day late with my period and very nervous if I could be pregnant. I took a pregnancy test about a month ago and it was negative. When I had sex, he used a condom and pulled out. When he removed the condom, it did not appear to be leaking or anything. Please help. Should I be concerned about pregnancy?